The invention relates to a stomach tube with a suction tube which has adequate dimensions for drawing out the stomach contents, with a stomach balloon and with a nose plug for fixing the tube in the intended position.
It has not to date been possible to eliminate the aspiration of acidic stomach contents into the bronchi as cause of anaesthetic deaths (Anaesthesist, 1987, 36:599-607). The induction and reversal phases of anaesthesia are particularly critical, during the introduction and removal of the endotracheal tube, because the irritation of the pharynx is particularly great during these phases, and the tube is not yet or no longer locked in the trachea by a cuff which, during the normal posi-tioning of the tube, generally prevents the penetration of stomach contents into the bronchi, except in the case of paediatric tubes which have no cuff. There is an increased risk in non-fasting patients (emergency patients) and where there is increased pressure on stomach and intestines (pregnancy, ileus). In these cases, the stomach contents are aspirated using a normal stomach tube before the siting and withdrawal of the endotracheal tube. However, this does not achieve safety because evacuation is generally incomplete and intestinal contents may get back into the stomach. The insidious aspiration of stomach contents may be responsible for pneumonia in intensive care patients ventilated for a long time.
It is the intention of a known tube of the type mentioned in the introduction (DE-A 24 12 553) to counter this disadvantage by having a stomach balloon which, after the tube is sited in the stomach, is inflated and is intended to be in contact with the stomach inlet in such a way that reflux of the stomach contents is prevented. The balloon is intended to be secured in this position by the instrument being retracted, after the stomach balloon which is lying free in the stomach has been inflated, until a resistance indicates that the stomach balloon is in contact with the stomach inlet. After this a cuff which is located in the region of the oesophagus is inflated with the intention of securing the tube, by its friction on the wall of the oesophagus, in the intended position and forming an additional resistance to reflux of stomach contents. However, this tube has not found wide use. Because of the risk of perforation, the oesophageal cuff may contain only relatively low pressure. Since the oesophagus, because of anomalies inter alia, may have very different diameters, the oesophageal cuff must be designed to be relatively wide. This means that, when the inflation pressure is low, it is unable to secure the axial location owing to the possibility of quasi rolling deformation of its ends in opposite directions. This disadvantage cannot be prevented by the presence of an external control balloon which merely indicates the state of inflation of the cuff.
Also known is a tube which has a stomach balloon and an oesophageal balloon, which are used for compression of the superficial vessels in the oesophagus and at the stomach inlet in order to stop bleeding (U.S. Pat. No. 3,046,988). The tension in the suction tube which is intended to ensure the correct position of the stomach balloon is, moreover, intended to be maintained by a nose plug. However, preferred in practice for these cases is, despite the inconvenience associated therewith, a weight-loaded tension thread connected to the suction tube (Sengstaken tube, public prior use), because the amount of tension can be determined easily and reliably thereby. In general, nose plugs are used only in those cases (mainly in the case of endotracheal tubes) where only low fixing tensions occur and there is no need for these to be accurately maintained. The reason for this is that the frictional state of a nose plug on the relevant tube can vary widely depending on how much discharge is adherent to the tube surface. Thus, according to present knowledge, a nose plug is unsuitable for uses in which a predetermined and high tension has to be applied--as in the case of the stomach tubes provided as class by the invention--especially since the importance of maintaining the predetermined tension increases with the tension.
However, the invention has recognised that a nose plug or nose stop is very suitable for maintaining a high suction tube tension which is predetermined within narrow limits when the method according to the invention for siting the tube is used. This method is distinguished by the stomach balloon being inflated in the stomach, with the tube free of tension, until a lower pressure level is reached, and then being brought to a higher pressure level by tensioning the suction tube and the contact, which is brought about thereby, with the stomach inlet, and the tube being fixed in this state by means of the nose plug. The implementation of this method with a stomach tube according to the invention is made possible by the separate lumen, which is connected to the stomach balloon, of the tube being connected in the external region of the tube to a pressure-control device which is equipped to indicate at least two pressure levels, of which the lower is assigned to the freely inflated state and the higher is assigned to the state of the stomach balloon in contact with the stomach inlet under the tension of the tube.
It is known to connect tube balloons to external test balloons (DE-A 35 09 797, DE-C 33 03 582, DE-A 34 12 553, DE-A 36 10 091) which, however, indicate only the inflation state as such, not the inflation pressure however. It is also known to use a control balloon with pressure indicator for particular uses (U.S. Pat. No. 4,185,638). In the case of stomach balloons for devices of this class, such a pressure indicator has not to date been worthwhile because it has provided no information on the contact pressure which always depends on the tension of the suction tube, and was thus not obvious. In addition, there is the following fundamental difference between the latter and the invention. In the known cases, the external pressure-control device controls directly the pressure which is to be achieved by introducing compressed air, and the latter is stopped when the desired pressure has been reached according to the indicator on the device. The only correspondence with this known use in the case of the invention is the lower pressure level. By contrast, the upper pressure level is not used for controlling the introduction of pressure, nor actually for controlling a pressure, but for controlling the tension of the suction tube. Thus, a very simple and accurate means of establishing the tension of the suction tube is made available and then makes it possible to use a simple fixing means, namely the nose plug.
Whereas the tension of the suction tube remains constant when a tension thread arrangement is used, irrespective of any movements of the patient, such movements may have an effect on the tension in the suction tube when a nose plug is used. In order for the changes brought about by this to remain small, it is expendient for the suction tube to have tensile elasticity.